Process of extracting products from wood.



W. B. HARPER.

PROCESS OF EXTRAGTING PRODUCTS FROM WOOD.

APPLICATION FILED MAY 22, 1912.

1,085,416. Patented Ja11.27,1914.

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ATTORNEYS UNITED STATES PATENT OFFICE.

WALTER B. HARPER, OF LAKE CI-IAZRLES, LOUISIAEA, ASSIGNOR OF ONE-HALF TO THE CASTONA IMPROVED PROCESS ('10., OF LAINE, MISSISSIPPI, A CORPORATION.

PROCESS OF EXTRACTING PRODUCTS FROM WOOD.

Specification of Letters Patent.

Patented Jan. 27,1914.

Application filed May 22, 1912. Serial No. 699,010.

To all whom it may concern Be it known that I, VALTER B. HARPER, a citizen of thUnited States, and a resident of Lake Charles, in the parish of Calcasieu and State of Louisiana, have invented a new and Improved Process of Extracting Prod ucts from 00d, of which the following is a full, clear, and exact description.

My invention relates to a process of extracting resin, turpentine and pine oils from resinous and coniferous wood.

By my improved process I extract the turpentine and other light volatile terpenes by means of live steam under low pressure and temperature followed by superheated steam under any desired pressure and at a temperature sutlicient to remove the pine oils from the wood, and, subsequently, treat the remaining resinous material with a suitable solvent, the resin and solvent being afterward separated to obtain the pure resin.

The expression low pressure and temperature as herein employedrepresents treatment of the wood with live steam, the pressure increasing toward the end of the operation, but not to exceed twenty-five pounds, the temperature, of course, increasing with the pressure. At the start the operation could be under a vacuum, if desired. The several processes now in use in this art are objectionable for the reason that when the resin is extracted by a solvent without first removing the turpentine from the wood, it is very difficult to separate the turpentine from the solvent unless expensive solvents are used. l/Vhen the turpentine has been previously removed by a low pressure steam, as iscustomary with the present steam turpentine-distilling processes before the treatment of the wood with the resin solvent, pine oils are not extracted except possibly in small quantities which distil with'the turpentine. These pine oils are compounds having a high boiling point as compared with turpentine, and, ave, consequently, a boiling point intermediate those of resin and turpentine. Being heavy oils with a low vapor tension, low pressure steam does not remove them except in very small quantities. These ,pine oils are extracted with the resin when the wood is treated wi h asolvent, and the residue produced upon the distillation of the solvent, is not resin proper but a soft pitch-like substance consisting of pine Oll, resin and other foreign matters extracted from the wood. The pine oils cannot be removed from this mixture by distillation without darkening the color of the resin, and if dried at a lower temperature. the resin is likely to be soft and to conta n the odoriferous properties of the wood, thereby rendering the resin unsuitable for many arts.

To obviate the above-outlined difliculties and to produce commercial articles of a higher degree of purity, I inject into a mass of wood contained in a suitable vessel, live steam at a low temperature and pressure, by means of which the turpentine and possibly a small portion of the pine oil are caused to distil over to a suitable condenser, leaving the water, a large portion of the pine oils, and resin still in the wood. I then subject the wood remaining in the vessel to superheated steam under suitable pressure, the temperature being so regulated that neither the wood nor the resin is decomposed. This treatment serves to remove the water and most of the pine oils, and leaves the wood in an excellent condition for further treatment by a solvent. This dissolving treatment consists in subjecting the wood to a volatile solvent, preferably some cheap neutral hydrocarbon, hot or cold, which has the oll'vel. of extracting the resin from the wood. The resin in solution is then drawn oil", and, if necessary, the wood remaining is steamed to remove-any solvents adhering thereto.

If the solution of resin in the solvent is without the impurities from the wood, I distil the solvent and resin without refining it; but if the solvent is of such a nature that it removes not only the resin but the impurities from the wood, I mix this solution of solvent and resin while still hot with a solution of a suitable refining agent, such as an alkali or acid, according to the character which it is desired to be given to the refined product. It is generally preferable to give a slight alkaline character to the retinlng substance. The so-formed mixture of the solvent and refining substance must be entirely stirred and then left undisturbed to permit the settling of the different substances by gravity. The sediment, consistin of impurities acted on by alkali or acid, being the heaviest will be found in the lower part of the container, and the solution of solvent and resin can then be drawn off and be distilled so as to recover the solvent, and the remaining residue will be resin, which may be afterward treated for better color and consistency.

. The impurities, waxes, resemble rosin but are the product. ,are turpentine, naphtha, benzol and similar volatile hydrocarbons. A 1% solution of acid and alkali is generally to be used. For a very-high grade of rosin a strong acid solution is used followed by the weak alkali.

The solvents used may be any of the ordinary light petroleum or tar oils, but I have found that turpentine and other light oils produced by distilling soft woods, resins and pine tar, particularly after such oils have been refined, are the best kinds of solvents for this purpose.

While the above-outlined process ma be carried out in any suitable receptacle, I ave found from experience that an economical treatment is attained by placing the wood in or fatty substances, and injurious to a single receptacle, but, preferably, a battery of receptacles, so that the difierent steps may be carried on simultaneously or in succession in the several receptacles.

Reference is to be had to the accompanying drawings, in which the figure is a view partly in section, showing two receptacles of a battery by means of which my improved process may be readily carried out.

The resinous Wood cut in' blocks or finely comminuted, is placed in a suitable retort, still or receptacle 1, and steam is introduced into the receptacles from a steam pipe 2 and into the coils 3 disposed below the perforated false bottom 4 of the receptacle. The steam being preferably maintained at a pressure below twenty-five pounds, the turpentine steamed ofi from the wood in the receptacle passes through the outlet 5 to the condenser 6, from which it is collected in a suitable tank, not shown. The contents of the receptacle 1 is then treated to superheated steam introduced through the steam pipe 7, the temperature being raised so as to remove the pine oils. As soon as the pine oils are removed, the superheated steam is shut ofi' by means of a valve 8, and the solvent is then pumped into the retort through a pipe 9 and heated by the steam in the coils 3. This solvent dissolves the resin from the wood in the retort and then passes through a pipe 10 to a second retort 11 in The solvents usually employed.

of the discharge p pe the series, which retort and all succeeding retort-s in the battery are going through the processes in succession.

previously outlined The pressure refers to the pressure in the extractor, or retort, and not in the boiler. The inlet valve of the extractor is preferably smaller than the outlet valve to the condenser and it would be necessary to close the condenser valve partially in order to produce pressure in the extractor. The temperature of the superheated steam would probably range about 600 to'800 degrees Fahrenheit. mitted steam does not materially affect the operation, but it is the amount of this hot steam which enters the extractor that accomplishes the results. It should be admitted in such quantity that the temperature The temperature of this ad-' of the extractor will not rise above 300 degrces Fahrenheit. Results may be obtained at lower temperature, but more time is required.

After the solution has extracted the desired amount of resin, it is conveyed to a storage or separating tank, not shown, and is then ready for further treatment as previously described.

New solvent may be introduced to the first retort, and the process continued until all of the resin has been extracted. By means 12, the solvent remainresln has been extracted is allowed to flow from any of the retorts, the oil adhering to the wood is distilled, and the wood remaining in the retort is removed and the retort cleaned.

When turpentine is used as the solvent the wood which is in a finely comminuted form is treated with the turpentine until the desired amount of resin has been removed; then the solution is drained off and the remaining turpentine adhering to the wood is steamed ofl". The solution of resin and turpentine is then heated and the turpentine is removed therefrom by the application of steam. This phase of the process is very important when the wood is to be used for paper making.

Having thus described my invention, I claim as new and desire to secure by Letters Patent:

The process of distilling wood, consisting of treating wood in a suitable container by distillation in a current of steam of low pressure and temperature, thereby carrying off the turpentine, then condensing the vapors and separating the turpentine from the water, then again subjecting the wood in the container to a stream of superheated steam at such a temperature as will not injure the wood or rosin but only carry off the oils ing after the from the wood, then condensing the vapors and 'separatin the oil and water, then treathot wit-h a solvent of neutral hydrocarbon which dissolves the rosin contained in the Wood and is then drawn ofl" into a separate container Where it is distilled, thus leaving the rosin as a residue, and recovering the solvent b condensation.

In testimony whereof I have signed my name to this specification in the presence of two subscribing Witnesses.

WALTER B. HARPER.

Witnesses WARREN A. Mix, JAY P. MIX. 

